The winner of this year's Bathurst 1000 may not be confirmed for at least another week despite Jamie Whincup failing to overturn a penalty that cost him a fifth Great Race victory.

The Supercars National Court of Appeal's dismissal of Whincup's appeal on Tuesday night ensured provisional winner Holden's Will Davison and co-driver Jonathon Webb's grip on the Peter Brock Trophy tightened.

However, Whincup's Red Bull Racing (RBR) team have a week to decide whether to take their case to the FIA International Court of Appeal.

Whincup crossed the line first on the October 9 race but was relegated to 11th due to a 15 second time penalty for his role in a late incident that ended the winning hopes of Volvo's Scott McLaughlin and Holden's Garth Tander.

Triple Eight Race Engineering entry RBR appealed the severity of the time penalty but it took just 50 minutes for the three-man Supercars Court of Appeal panel to dismiss it.

"Supercars welcomes the decision ... in relation to Triple Eight's appeal of a steward's decision at the Bathurst 1000," Supercars chief executive James Warburton said.

"We look forward to this weekend's Gold Coast 600 and an exciting conclusion to the 2016 Supercars championship over the coming months."

However, it may be another week before Davison and Webb can officially celebrate a Bathurst 1000 win.